1. Field of the Invention
The invention relates to a competition firearm, especially a rifle or pistol, having an action including a breech casing which is guided in the firearm so as to be longitudinally displaceable on bearings and which counteracts the recoil during firing and to which the barrel and other firearms parts are fastened, if appropriate, for the purpose of increasing weight. Competition firearms of this type are known as compressed-air firearms having a piston, cylinder and compression spring. In addition to this, however, they are also used as firearms for cartridge ammunition.
The action mounted displaceably in the firearm is moved, during firing, as a result of the recoil in the direction opposite to the departing bullet. The bearings are designed and aligned so that they permit movement in this direction only. Consequently, the recoil cannot be transmitted to the action-carrying parts of the firearm (stock), and the latter is recoiless towards the outside. The recoil energy which is expressed in the kinetic energy of the action is used up by means of bearing friction and, if necessary, by means of a soft buffer which takes effect at the end of the return travel. The bearings in which the action runs are metallic plain or roller bearings which are fastened rigidly to the action and to the action-carrying firearm parts.
2. Description of the Prior Art
An example of a recoilless compressed-air firearm, the displaceable action of which is guided in at least two prismatic linear roller bearings arranged parallel in the stock, is given in German Patent Specification No. 1,140,489. The action of a recoilless shoulder weapon which has become known is also equipped with similar prismatic roller bearings.
In a recoilless compressed-air firearm according to German Patent Specification No. 1,147,142, the front end of the action on the barrel side is mounted by means of two cylindrical bolts arranged parallel to the longitudinal axis of the action and at a lateral distance from one another in two corresponding bores in a support fastened in the stock. As a result of the transverse distance between the bearing bolts, the action is prevented from tilting sideways. The rear end of the action is supported displaceably by means of an axis-parallel bore on a bolt fastened in the same line in the stock.
Another recoilless compressed-air firearm which is described in German Patent Specification No. 2,329,425 is also knonw. In this firearm, an essentially cylindrical action to which the barrel is also fastened is mounted so as to be longitudinally displaceable, by means of cylindrical linear roller bearings arranged concentrically to the main axis, in a tubular metallic sleeve connected fixedly to the stock. A further bearing attached off-center to the action prevents the action from rotating about its main axis.
In all these firearms, it is necessary for the axes of movement of the action bearings to be aligned absolutely parallel or in one line. Moreover, if appropriate, the distances between the axes of the bearings and the distances between the parts mounted therein must correspond exactly. And finally, it is also necessary for the bearing geometry to have the appropriate accuracy. If these conditions are not satisfied, the bearings jam or cannot be assembled at all in the first place. Consequently, it is necessary either to ensure a high degree of accuracy in the production of the parts in question or to make the bearing play correspondingly large. The first is expensive and the other lowers the firing accuracy of the weapon, which is understandably undesirable.
However, the interaction of the various bearings is influenced adversely not only by dimensional and positional variations caused by production, but also by changes in position which do not arise until the firearm is used. Changes in position of this type can be caused, for example, by uneven fluctuations in temperature of the firearm parts, by mechanical loads and by variations of moisture in stocks made of wood or plastic which, under certain circumstances, also lead to distortions of the action bearings.
To mitigate these difficulties, an attempt was made to design at least one of the three action bearings as a so-called loose bearing which is insensitive to possible positional variations and changes in position. The other two action bearings had to be designed as before, as fixed bearings without the possibility of compensating positional variations and changes in position, in order to guarantee secure mounting of the action in an invariable location.
An action mounting designed according to this principle for a recoilless air rifle is illustrated and described in German Offenlegungsschrift No. 2,512,476. In this publication, in a similar way to the above mentioned compressed-air firearm according to German Patent Specification No. 1,147,142, the action is mounted so as to be longitudinally displaceable in the rifle stock by means of three cylindrical bearings bolts arranged parallel to one another. Two of the three bearing bolts at the front and rear ends of the breech casing are guided displaceably in metallic prismatic guide grooves. The third bearing bolt is supported on a flat horizontal in the position of use of the firearm and therefore undergoes no lateral guidance. To ensure that the action rests securely in the open bearings, it is pressed down by springs as well as by its own weight, or the bearing bolts are pressed into the bearings by means of small plastic blocks, the pressing force being variable by means of adjusting screws.
In this construction, the problem of compensating the positional variations is solved only partially for the one bearing with the flat supporting plate. However, even here, a positional variation, caused because the supporting plate and the bearing bolt are not parallel, cannot be eliminated and results in an undesirable edge pressure. It is also unfavorable that all three bearings have to be loaded by additional holding-down forces, thus increasing the friction and wear.